The present invention relates to the field of metering the vapours contained in a given atmosphere, by condensation in contact with a cold source.
It particularly, but not exclusively, applies to the case of the continuous determination of the water content of the atmosphere and is used with particular advantage when it is a question of monitoring, in the vicinity of nuclear installations which can lead to radioactive pollution, the content of radioactive constituents in the water of the atmosphere. Thus, for example, use is presently made thereof in the determination of the tritiated water content of the earth's atmosphere in the vicinity of certain nuclear installations.
The industry is already aware of certain equipment making it possible, by condensation, in contact with a cold source, of the vapours contained in the atmosphere, to identify and meter said vapours.
Thus, equipment is known, which traps the vapours by solid carbon dioxide, but suffer from the disadvantage of requiring a permanently replenishable stock of solid carbon dioxide for ensuring their satisfactory operation.
In other known equipment, use is made of ordinary refrigerating units, in which the atmosphere containing the vapours to be condensed plays on the cooled walls of said unit. This type of apparatus has the serious disadvantage caused by the fact that, after a certain time, the ice which forms on the walls constitutes an obstacle to the transmission of the cold fluid and rapidly reduces the efficiency of the installation after a few hours. Moreover, such equipment only functions discontinuously and is not very practical, because someone must be permanently present to recover the hoar frost which forms on the walls.
Equipment is also known, which traps the water vapour in the air by effecting its bubbling in an aqueous solution. These systems have the disadvantage of being limited both with respect to the flow rate and the operating period, whilst also requiring daily maintainance.